The top is also the top on the guitar, the thickest string is on the left (low sound). The standard tuning is used; E A D G B e.
The dots indicate where you should push on the strings, And the numbers indicate the finger you should use. It doesn't really matter which finger you use, these are suggestions, There is no perfect placing, it depends on what you are going to do next. When its a stripe/dot, you use a barre. (using 1 finger on more strings)
X: The string is muted or not played at all.
0: The string is played without pressing it anywhere on the fretboard.
The colors indicate Skill level. This is different for everyone and is meant as a guideline.
green = easy | yellow = normal | red = hard